Critical properties of the metal-insulator transition in anisotropic systems

We study the three-dimensional Anderson model of localization with anisotro pic hopping, i.e., weakly coupled chains and weakly coupled planes. In our extensive numerical study we identify and characterize the metal-insulator transition by means of the transfer-matrix method. The values of the critic al disorder W-c obtained are consistent with results of previous studies, i ncluding multifractal analysis of the wave functions and energy-level stati stics. W-c decreases from its isotropic value with a power law as a functio n of anisotropy. Using high accuracy data for large system sizes we estimat e the critical exponent as v = 1.62 +/- 0.07. This is in agreement with its value in the isotropic case and in other models of the orthogonal universa lity class.